<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>降域</title>
  <style>
  .ct{
    width: 910px;
    margin: auto;
  }
  .main{
    float: left;
    width: 450px;
    height: 300px;
    border: 1px solid #ccc;
  }
  .main input{
    margin: 20px;
    width: 200px;
  }
  .iframe{
    float: right;
  }
  iframe{
    width: 450px;
    height: 300px;
    border: 1px dashed #ccc;
  }
</style>
</head>
<body>
  <div class="ct">
  <h1>使用降域实现跨域</h1>
  <div class="main">
    <input type="text" placeholder="http://a.jrg.com:8080/a.html">
  </div>

  <iframe src="http://b.jrg.com:8080/b.html" frameborder="0" ></iframe>

</div>

<script>
//URL: http://a.jrg.com:8080/a.html
document.querySelector('.main input').addEventListener('input', function(){
  console.log(this.value);
  window.frames[0].document.querySelector('input').value = this.value;
})
document.domain = "jrg.com"
</script>
</body>
</html>








